This invention pertains to ball valves or other valves characterized by the movement of a handle through 90.degree. to open or close the valve. Interacting stop means on the handle and on the valve body limit the swing of the valve handle to the 90.degree. arc to position the valve ball or its equivalent in either a full open or full closed position. A recurrent problem in such valves is the provision of means to insure that the valve will not be accidentally displaced from either its full open or full closed position. The problem is particularly acute in the conventional ball valve when it is positioned in the full closed position at which time the handle extends transversely out from the valve and the line it is situated in. Such an outstanding handle provides a ready target for passing traffic.